Identification of human liver cytochrome P-450 3A4 as the enzyme responsible for fentanyl and sufentanil N-dealkylation

Anesth Analg. 1996 Jan;82(1):167-72. doi: 10.1097/00000539-199601000-00031.


Alfentanil, sufentanil, and fentanyl are synthetic opioids that are metabolized by oxidative N-dealkylation in the liver. We have previously shown that cytochrome P-450 3A4 (CYP3A4) contributes significantly to human liver microsomal alfentanil oxidation. Since identification of specific drug-metabolizing enzymes allows prediction of the variables affecting drug metabolism, the purpose of the present study was to identify the P-450 enzymes responsible for sufentanil and fentanyl metabolism in human liver microsomes. Microsomal preparations fortified with a reduced nicotinamide-adenine dinucleotide phosphate-generating system were incubated with 0.25 microM 3H-fentanyl or 3H-sufentanil. Rates of N-dealkylated metabolite formation significantly correlated with nifedipine oxidation activity (a marker of CYP3A4 activity) for fentanyl and sufentanil (r = 0.93 and 0.87, n = 18, respectively), but not with the oxidation activity for ethoxyresorufin (CYP1A2), S-mephenytoin (CYP2C19), bufuralol (CYP2D6), or chlorzoxazone (CYP2E1). Gestodene and troleandomycin (chemical inhibitors of CYP3A4) and antibody to CYP3A4 inhibited N-dealkylation of fentanyl and sufentanil. Chemical inhibitors of CYP2C, 2E1, and 2D6 did not inhibit N-dealkylation of fentanyl and sufentanil. Recombinant CYP3A4 expressed in Escherichia coli showed N-dealkylation activity of fentanyl and sufentanil, while expressed CYP1A2, 2C10, and 2E1 enzymes did not. We conclude that CYP3A4 is responsible for fentanyl and sufentanil N-dealkylation in vitro.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analgesics, Opioid / metabolism*
  • Animals
  • Antibodies / pharmacology
  • Antibody Specificity
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme Inhibitors
  • Cytochrome P-450 Enzyme System / immunology
  • Cytochrome P-450 Enzyme System / metabolism*
  • Dealkylation
  • Enzyme Inhibitors / pharmacology
  • Erythromycin / pharmacology
  • Fentanyl / analogs & derivatives
  • Fentanyl / metabolism*
  • Humans
  • Kinetics
  • Liver / enzymology*
  • Microsomes, Liver / enzymology
  • Mixed Function Oxygenases / antagonists & inhibitors
  • Mixed Function Oxygenases / immunology
  • Mixed Function Oxygenases / metabolism*
  • Norpregnenes / pharmacology
  • Rabbits
  • Sufentanil / analogs & derivatives
  • Sufentanil / metabolism*
  • Troleandomycin / pharmacology


  • Analgesics, Opioid
  • Antibodies
  • Cytochrome P-450 Enzyme Inhibitors
  • Enzyme Inhibitors
  • Norpregnenes
  • norsufentanil
  • Gestodene
  • norfentanyl
  • Erythromycin
  • Cytochrome P-450 Enzyme System
  • Sufentanil
  • Troleandomycin
  • Mixed Function Oxygenases
  • CYP3A protein, human
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Fentanyl